The Bureau of Reclamation announced that it has begun the annual "flip-flop" operation in the Yakima Basin by gradually reducing flows in the upper arm of the Yakima River and increasing flows in the Naches River with increased water releases from Rimrock Reservoir.

The purpose of the "flip-flop" operation is to encourage spring Chinook salmon to spawn at relatively low flows so that less water is required during the winter to keep the egg nests, also known as redds, covered. This water operation also reduces impacts on irrigation water supply during the next season.

On September 3, Reclamation will begin to route water down the Kittitas Reclamation District's spillway into the Yakima River near Thorp, Wash.

Reclamation will install buoys around the area where the spillway flow impacts the Yakima River. The buoy system will remain in place for the duration of "flip-flop," which should last approximately 45 days. The floating buoys, about the size of 30-gallon drums, serve as a warning to recreationists to stay out of the turbulent flows. Recreationists should portage around this area.

Flows out of Cle Elum Reservoir will gradually decrease from the current flow down to between 200 to 250 cfs by about September 15 or sooner. Flows from Rimrock Reservoir are expected to increase from the current flow up to near 2,000 cfs by mid-September and could possibly reach 2,200 to 2,400 cfs, depending upon irrigation demands and weather conditions. Rimrock Reservoir is impounded by Tieton Dam and located about 40 miles northwest of Yakima, Wash.

Stream flow changes will occur gradually during the Labor Day holiday weekend. Streamflow information can be obtained by calling (509) 575-5854 or on the internet at: http://www.usbr.gov/pn/hydromet/yakima/index.html.

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Reclamation is the largest wholesale water supplier and the second largest producer of hydroelectric power in the United States, with operations and facilities in the 17 Western States. Its facilities also provide substantial flood control, recreation, and fish and wildlife benefits. Visit our website at www.usbr.gov and follow us on Twitter @USBR.